Sally Ride, an astronaut and physicist who in 1983 became the first American woman sent into space and reluctantly served as an idol of feminist strength and a hero of women’s progress, died Monday at her home in La Jolla, Calif. She was 61.

She had pancreatic cancer, said Terry McEntee, her assistant.

Ms. Ride made history on June 18, 1983, when she orbited the Earth aboard the space shuttle Challenger. At 32 years and 23 days old, she was the youngest American to go into space.

In a statement, President Obama said that Ms. Ride “inspired generations of young girls to reach for the stars.”

He continued, “Sally’s life showed us that there are no limits to what we can achieve and I have no doubt that her legacy will endure for years to come.”

Yet the legacy Ms. Ride had earned as a space pioneer was one that she was reluctant to embrace. She rarely gave interviews, enjoyed not being recognized in public, and — unlike some of the daredevil pilots in the first class of astronauts — avoided attracting attention to herself and her achievements.

She maintained from the beginning that she had not intended “to become a historic figure or a symbol of progress for women.” At her request, NASA denied all requests for licenses to sell posters, T-shirts and other merchandise bearing her name and likeness.

For Ms. Ride, a theoretical astrophysicist, the real accomplishment of her debut journey into space was an experiment in which a 50-foot robotic arm was maneuvered to grasp a three-ton satellite hurtling above Earth.

At a NASA news conference, she told reporters: “It’s too bad this is such a big deal. It’s too bad our society isn’t further along.”

She was aware that two Russian female cosmonauts had preceded her into space, Valentina Tereshkova in 1963 and Svetlana Savitskaya in 1982.

Ms. Ride would fly to space only one more time, in a 197-hour mission again aboard the Challenger. It included observations of the Earth using satellites and high-tech cameras.

She had been scheduled to make a third trip, but it was canceled after the Challenger exploded Jan. 28, 1986, killing six NASA astronauts and teacher Christa McAuliffe. After serving on a presidential commission investigating the disaster, Ms. Ride resigned from NASA and turned to academia, as a physics professor at the University of California at San Diego. In 1986, she and former Washington Post staff writer Susan Okie published, “To Space and Back,” a book describing Ms. Ride’s astronaut career.

In the decades afterward, she shunned opportunities that would have put her in the spotlight. She had once called spaceflight “the most fun that I’ll ever have in my life” and said that leaving the program was hard.

It could be said that in one way or another, all of her early life had been preparation to become an astronaut. Sally Kristen Ride was born May 26, 1951, in Los Angeles. Her father was a political science professor at Santa Monica College, and her mother helped found the Mary Magdalene Project, which helps prostitutes escape the streets. As a teenager, Ms. Ride had excelled as an athlete, especially in tennis, where she learned to think quickly. She was encouraged by mentor and playing partner Billie Jean King to consider turning professional.

Despite her skill, she decided to stop playing. At Stanford University, she demonstrated wide-ranging intellectual interests, from physics to literature.

“It’s kind of like doing puzzles,” she said. “You had to figure out what he was trying to say and find all the little clues inside the play that you were right.”

At Stanford, Ms. Ride answered a college newspaper advertisement and applied for a position at NASA, which was then trying to add scientists to its ranks. She beat out 8,370 other applicants and, armed with a doctorate in physics from Stanford, joined the astronaut corps in 1978.

Until then, the astronaut corps was widely regarded as something of a boys’ club of fliers, mostly Navy and Air Force men.

NASA needed more astronauts for the shuttles, with a large schedule of flights planned. For the first time, the agency opened the corps to women.

The June 1983 launch that sent Ms. Ride into orbit was carried on television and considered a historic occasion. That seventh shuttle mission — the second for the Challenger — teamed Ride with four men. Her commander, Bob Crippen, quipped that they would be known only as the guys going into space with Sally Ride.

“She was a great crew member,” Crippen said Monday. “I was honored to fly with her twice. She was an ideal example to young women everywhere, telling them they can be and do anything.”

On her first flight, Ms. Ride served as a mission specialist, the title given to scientist astronauts. Using the robotic arm, she helped deploy a 3,300-pound satellite into space and then, using the arm again, recaptured it and brought the device back into the shuttle’s cargo bay. The experiment demonstrated the feasibility for NASA to recover broken satellites, repair them aboard the shuttle and release them back into orbit.

Offering suggestions that benefited the female astronauts who came after her, she asked that NASA make the seats on the space shuttle adjustable, add a curtain for the restroom area and reshape the vacuum toilet.

In 1984, Ms. Ride returned to space for her second and last mission. Operating the Challenger’s robotic arm, she deployed a satellite and supported her astronaut classmate Kathryn Sullivan, who on that mission floated into the shuttle’s payload bay and became the first American woman to spacewalk.

Ms. Ride was “a strong, strong competitor,” Sullivan said in an interview with The Post. “She was always challenging herself and challenging you.”

Margaret Rhea Seddon, another astronaut classmate, said she was not surprised that Ms. Ride was chosen ahead of the five other women. “Sally was definitely a standout from the very beginning. I knew she was very capable and she would represent us all well.”

In the mid-1980s, Ms. Ride donated her first flight suit to the Smithsonian National Air and Space Museum, where it hangs inside a mock-up of a space shuttle. The light-blue jacket bears a name tag that says, simply, “Sally.”

After her space career, Ms. Ride devoted herself to bringing the excitement of science to children — especially girls. She helped found the Challenger Center for Space Science Education, based in Alexandria, and in 2001 launched Sally Ride Science, an educational company. She also co-wrote several books for children.

Ms. Ride’s marriage to astronaut Steve Hawley ended in divorce. Survivors include her mother, Joyce; and a sister. She is also survived by her partner of 27 years, Tam O’Shaughnessy. The two women co-wrote several books, including “The Third Planet” (1994), which won the American Institute of Physics Children’s Science Writing Award.

Upon their completion of the 1983 mission, President Ronald Reagan congratulated the astronauts on a job well done. Acknowledging Ms. Ride, he told her: “You were the best person for the job.”